1. Field of the Invention
The present invention relates to the field of toy vehicles.
2. Prior Art
Toy vehicle guidance systems of various types are well known in the prior art. Each of these guidance systems has certain advantages and disadvantages that characterize the system. Since the present invention is particularly (but not exclusively) suited to toy vehicle racing applications, certain prior art relating to toy vehicle racing applications will be discussed.
Electric racing sets commonly referred to a xe2x80x9cslot vehiclesxe2x80x9d use plastic flat roadway with protruding embedded wires that are formed on the ends into electrical connectors. The plastic tracks are molded to have interlocking connectors to connect the plastic roadway together. The tracks are made with straight lengths and curved lengths which when connected together form the raceway. The vehicles pickup motive current from the track through brushes attached to the vehicles that contact the track wire. The vehicles are aligned on the track through a protruding pin on the vehicle that rides in a xe2x80x9cslotxe2x80x9d molded into the track.
The advantages of slot vehicle race sets include:
1. They are easy to use as there is only throttle control
2. No batteries are required
The disadvantages of slot vehicle race sets include:
1. Embedded Wires connectors are fragile
2. Wire connections are unreliable
3. Plastic interlocking connectors are fragile
4. Vehicles pickup power from the embedded wires and this connection is unreliable
5. The roadway is expensive
6. The scale is typically limited due to roadway cost
7. Racing is limited to existing pathways with one vehicle in left lane and one vehicle in right lane
8. Pathway design is limited due to preformed straight and curved lengths
9. There is no steering control
Also known are race vehicle sets known as hyper racers. Hyper racers use plastic U shaped track without embedded wires. Battery powered vehicles are placed in the U channels for racing. The vehicles fit completely inside the U channel. Vehicles are speed controlled through a radio link or the vehicles have no speed control at all and travel at a constant rate. The vehicles are centered in the U track through small idler wheels that protrude out the sides of the vehicle.
The advantages of hyper racers include:
1. Ease of use as there is no steering control
2. No embedded track wires are used
Disadvantages of hyper racers include:
1. Use rollers on side of vehicle to navigate through track
2. Racing is limited to existing pathways
3. Racing control is limited to speed control only through Radio link
4. The roadway is expensive
5. The scale is typically limited due to roadway cost
6. There is no steering
7. The pathway design is limited due to preformed straight and curved lengths
Also well known are radio controlled vehicles, which use no track at all. The vehicles are battery powered and are typically speed and steering controllable through a radio link. The absence of a track and the use of the radio link for control gives radio controlled toy vehicles a degree of flexibility not found in other toy vehicle navigation systems. As a navigation system for race vehicle sets however, pure radio control of all functions is less than optimum.
The advantages of radio control in general include:
1. There is no track required
2. There are no wires required
3. Radio control allows free form play without tracks
The disadvantages of complete radio control in race vehicle sets include:
1. Racing is difficult, as radio control requires great skill
2. Racing in a confined space is difficult as control skill goes up as track scale goes down
Two wire navigation system are also known, as in the earlier invention of the present inventor disclosed in U.S. Pat. No. 5,175,480. This early toy vehicle navigation system used flat flexible plastic roadway formed into curved and straight lengths. The roadway did not have xe2x80x9cslotsxe2x80x9d or xe2x80x98U Channelsxe2x80x9d to position the vehicles on the roadway. The flat plastic roadway segments allowed two wires to be inserted into the sides of the roadway. The wires were energized with an alternating half cycle AC current, one half cycle of current on the inside wire of the track followed by an opposite polarity half cycle current on the outside wire of the track. The vehicle sensed the respective magnetic field of each wire through a coil placed on the centerline of the vehicle in front of the front wheels. The location of the vehicle between the two wires was determined by comparing the half cycle energy picked up from each wire by the coil in the vehicle. The steering system of the vehicle was responsive to the sensed position of the vehicle on the track. Lane position and vehicle speed were responsive to modulation of the current in the two wires.
The advantages of this two wire system for toy race vehicle sets include:
1. It allowed speed control and lane changing between the wires of the track
2. It provided good racing environment as vehicles traveled along a predetermined pathway
The disadvantages of this two wire system for toy race vehicle sets include:
1. It required plastic track to accurately separate wires a predetermined distance
2. The plastic track is expensive
3. It used single turn wire track loops which generated a very small magnetic field
4. The weak magnetic field caused noise immunity problems
5. The pathway design is limited due to preformed straight and curved lengths
It would be desirable to provide a toy race vehicle set having at least some of the following features, advances and advantages:
1. Eliminate the requirement of a track, such as the plastic tracks on which vehicle racing is confined in many race vehicle sets
2. Eliminate the requirement of embedded wires in a track, such as a plastic track
3. Provide guidance control for lane position
4. Allow lane changing
5. Allow multiple vehicles on the track at same time
6. Allow for a track racing environment in free form RC control
7. Allow for infinitely variable track configurations
8. Provide a magnetic control field with a single wire or single bundle of wires
Vehicle guidance and control systems that use the intensity of a field radiated from a source of radiation to define the track or lane for operation of the vehicles are disclosed. The source of radiation used is a single source of radiation in the sense that vehicle position relative to the source of radiation is sensed by sensing intensity of the radiation at the vehicle, rather than the difference in field intensity sensed from two physically separated sources of radiation. Exemplary embodiments using a single magnetic field for navigational control are described, including a basic system for a single vehicle, a tethered system having steering and speed controls for creating a multiple vehicle racing environment, and a radio controlled system, also for creating a multiple vehicle racing environment and in the embodiment disclosed, also useable as a stand alone RC controlled vehicle.